Books or pamphlets are generally rectangular in shape and include a long side and a short side. In the bookbinding industry, a signature is a folded, printed sheet, typically consisting of 16 or 32 pages, that forms a section of a book or a pamphlet. To construct a book, a block of signatures are first gathered together by a gathering machine. Next, the block is deposited into an elongated travel trough with the long side of the block abutting the bottom surface of the trough. The travel trough has a pair of parallel side walls adjustable to the width of the block to maintain the integrity of the block. The block is transported through the trough using a conveyor chain located adjacent the trough and carrying a plurality of pins extending laterally into the trough. Each of the conveyor pins engages a respective block deposited into the trough. To transport a deposited block to a binding machine, a downstream-moving pin engages the trailing short side of the block and pushes the block through the trough to the binding machine. Since the bound side of most books is the long side, the foregoing arrangement is usually sufficient. However, some books such as many children's books and cookbooks are often configured with the bound side being the short side so that the printed lines are parallel, rather than perpendicular, to the long side. Such books are often referred to as "oblong" books.
The gathering machine places all blocks of signatures into the travel trough with the long side abutting the bottom surface of the trough, whether or not the blocks are oblong in configuration. Therefore, in order for an oblong block to be correctly bound on the short side thereof, the oblong block must be turned ninety degrees prior to reaching the binding machine. One technique for turning oblong blocks employs a drop point along the trough. When an oblong block reaches the drop point, the block falls forward into a lower trough section with the block rotating ninety degrees in the process of falling. The block rotates because gravity causes the leading side of the block to fall prior to the trailing side.
A drawback of this technique is that control of the blocks is not maintained in the turning process. Instead, the blocks undergo an uncontrolled, jerky turning motion while they fall at the drop point. Another drawback is that the blocks are often damaged due to the lack of control in the turning process. More specifically, the falling and turning blocks temporarily space themselves ahead of the respective pins pushing the blocks through the trough. After the blocks land on the conveyor belt beyond the drop point, the pins "catch up" and strike the respective blocks, often damaging them in the process. Furthermore, the uncontrolled turning motion sometimes causes individual signatures in the blocks to shift relative to the other signatures in the block, thereby smearing the print on the misaligned signatures and the signatures adjacent the misaligned signatures and requiring downstream realignment of the misaligned signatures. Yet another drawback of the "drop" technique is that book turning is not consistent at different conveyor chain speeds or at different block sizes. To switch from one block size to another often requires reconfiguration of the drop point. A further drawback is that this technique often requires the supervision of an attendant to insure smooth operation and correct the above-identified problems.
Therefore, a need exists to overcome the foregoing drawbacks associated with existing techniques for turning oblong blocks of signatures.